This invention relates to analyzer systems, and more particularly to valve arrangements that have particular application in analyzer systems for analyzing parameters of biological fluids such as blood.
A blood gas analysis system of the type shown in Weinberg et al. U.S. Pat. No. 4,361,539 includes a module which houses a thermally-insulated integrated assembly with external electrical and fluid connections. That assembly includes, as an integrated unit, four electrode housings between which is disposed a precision flow through cell, two metal heater block assemblies with electrical heater pads for maintaining stable analysis temperature. Located centrally within the flow through cell is a spool valve assembly of the type shown in Ambers U.S. Pat. No. 4,298,026. That valve assembly cooperates with the electrode systems to selectively interconnect sample flow and calibrating fluid flow paths. In that valve, leakage has occurred when the spool valve is moved between positions, allowing sample material to be analyzed to travel along the surface of the valve spool and contact grounded portions of the valve assembly, creating instability and errors in the data measurements as well as interfering with valve operation.